Automatic fuel mixture control system



Feb. 26, 1946. c. A. TEICHERT AUTOMATIC FUEL MIXTURE CONTROL SYSTEM 7 Sheets-Sheet 1 Filed March 15, 1940 INVENTOR. 60/195 140 14. ff/J'Hffif BY; )4 f ATTORNEY.

7 Sheets-Sheet 2 c. A. TEIC4HERT Filed March 15, 1940 AUTOMATIC FUEL MIXTURE CONTROL SYSTEM Feb. '26, 1946..

Feb. 26, 1946. Q A c g 2,395,648

AUTOMATIC FUEL MIXTURE CONTROL SYSTEM Filed March 15, 1940 7 Sheets-Sheet 3 k} I INVENTOR. WV/F40 A. rims fir ATTORNEY.

Feb. 26, 1946. c. A. TEICHERT 2395,64

AUTOMATIC FUEL MIXTURE CONTROL SYSTEM Filed March 15, 1940 7 Sheets-Sheet fig; 4

INVENTOR. 00/1 5140 4. TA /6795i? TORNEY.

Feb. 26, 1946 I c. A. TEICHERT AUTOMATIC FUEL MIXTURE CONTROL SYSTEM 7 sheets-sheafv 5 Filed March 15, 1940 Q ammw 4. fz/aflmr BY QM, 4, QMW

- ATTORNEY.

NN mlwm c. A. TE IC HERT 2,395,648 AUTOMATIC FUEL MIXTURE CONTROL SYSTEM Filed March 15, 1940 '1 Sheets-Sheet s INVENTbR. can m0 ,4. ff/Y/[fl/ B EL. A @w ATTORNEY.

1 c. A. TEICHERT AUTOMATIC FUEL MIXTURE CONTROL SYSTEM Filed March 15, 1940 7 Sheets-Sheet 7 INVENTOR. v (ON/F40 4. Zf/flf/Tf BY ATTORNEY apparatus for the automatic'proportioning of the construction being somewha'fi simplified for meme i-feb. 26, 1 946 I 5, 43, I

PATENT AU'EQMATIC FUEL m'runn CONTROL SYSTEM Gonrad A. lleichert, Springfield, Mesa, assignor to American Bosch Corporation, Springfield, Mass, a corporation of New York Application March 15, 1940, Serial No. 324,151

a Claims; (oi. 261-69) This invention relates to a method of and ap- Figure 7 is a section taken on line 'l-l of Figparatus for automatically supplying an aircraft ure 2. engine with standard fuel-air mixtures of prede- Figure 8 is a longitudinal section through the termined values covering its complete range of ot or a tuat t e u ratio adjusting operation encountered in flight, which operation e hanism.

embraces acceleration, cruising, power, climb, Figure 9 S a Wiring d a of t e e ect c dive, all tactical maneuvers and glide. Circuits used n the comml System Another object of the present invention is to Figure 10 is a c v e of the fuel available a provide a suitable means to automatically control the aircraft engine within safe and economical 10 f Figure 11 is n upper face view of the fuel limits not requiring any undue consideration of w the pilot and allowing him the proper t t Figure 12 is a section on line 92-52 of the cam perform his primary duties which, in case of a shown in Fig. 11. military aircraft, involve not only ofiensive, but 1315aSectiontakenupnthe1ine-3i3l also defensive action. 15 ofFigure .12. l

More partic ]ar1y this invention aims to Figure 14 is a diagrammatic illustration of the vide a simple, reliable and accurate method and ratio regulator corresponding to Figure the relative mass-flows of fuel and air as required for poses of illustration and also showing fluid Pres afe' and economical operation f the engine sure connections between the ratio regulator and Other aims and advantages of this invention the air intake of the enginewm appear in the f ll i description, conskb Figure 15 represents a similar diagrammatic ered in connection with the accompanying view corresponding to Figure 3 and showing the drawinga fluid pressure connections between the fuel sup- In the accompanying drawings] in which like ply passage and pressure responsive devices reference numerals are used to designate similar g? the W parts throughout, there is illustrated a single em- 6 emng to the'drawmgs and pmmultfly to bodiment of preferred form of the invention, Figure 1, reference numeral l indicates an inter- The drawings, however, are for the purpose of 11- n0 :5 coznbugtion engnlle of i 2 z i lustration only and otherembodiments within 2 3} g 5 I the Scope of the appended claims will be appar' eral a crank case 2 upon wl i i h a re mountid a zgg g gfiz z fi g gafi lii f gglg gfi xig gg plurality of cylinders 3 extending radially from the crank case in one or more rows or banks. A fig igi gg j i'f' crank shaft t extends centrally through the crank F1 1 i t case and and is connected in the usual manner to we 15 agramma illustration of an pistons operative in the cylinders 3. One end of automatic mixture control system constructed in the crank shaft 5 projects through a nose piece accordance i h present invention 5 for a sufficient distance to permit the mounting figure s g fi 2 3 through a 40 thereon of an aeronautical propeller. 0 regu r W c S u iz n t e system- At th 0 site or rear end the crank shaft t Figure 3 is a section taken upon the line 3 -3 e ppo f is operatively connected to a supercharger 6,

o Figure 2. adapted to impel air drawn from an air intake Figliigur; 4 is a section taken upon the line 1-5 of conduit 5 past a fuel nozzle 8 positioned in a conduit leading to the air intake valve of one oi? the Figure 5 is a section taken upon the line 5-5 cylinders 3. It will be understood that preferably of. Figure 2. I a plurality of fuel nozzles 8 are provided, one for Figure 6 is a detail of an adjustable spring plate each cylinder, though it will be suflicient for preswhich forms a portion of the mechanism of the ent purposes to describe the operation of the conrat o ulat r. troi system in connection with hut one or them.

The fuel nozzle 8 is connected by means of con-- duit 9 to a suitable fuel pump or distributor Ill.

The air intake duct 1 opens toward the propeller and is provided at a point between this opening and the supercharger 6 with a venturi indicated at II. This venturi has an external diameter which is considerably less than the internal diameter of the air intake duct I and is maintained in a position centrally of the duct by 'a light web structure which offers little obstruction to the flow of air through the air intake passage 1. A conduit l2 having an opening into the throat of the venturi extends therefrom to a ratio regulator indicated generally at l3.

The detailsof the ratio regulator [3 are shown in Figure 2 and subsequent figures and referring particularly to Figures 2 and 14 it will be seen that the conduit [2 is connected to a cover [4 detachably mounted on a casing l5, which houses an internal, removable frame l6. supports and positions all of the parts of the mechanism forming the ratio regulator as hereinafter more fully described. The connection between the conduit l2 and the cover I4 is provided by means of an internally threaded boss I! on the cover and a passaged bolt l8 which extends through the cover l4 and into an internally threaded bore in the frame 16. The bolt is provided with suitable longitudinal and lateral passages to afford communication from the boss H to a passage IS in the instrument frame iii. A similar passaged bolt 28 extends from the exterior surface of the frame l6 into an interior chamber 2| of a bellows 22. The bellows 22 is provided with a head 23 having an inwardly projecting interiorly threaded annular boss to accommodate the passaged bolt 28 and a similar boss to accommodate thethreaded end of a screw bolt 24, these two bolts serving to rigidly position the head 23 of the bellows 22 upon the interior of the instrument frame 16. An adjusting screw 25, accessible from the exterior of the instrument frame, pro ects through the central portion of the head 23 and provides an adjustable bearing for positioning a spring 26 the opposite end of which bears upon a suitably reinforced portion of the opposite end wall of the bellows 22. A connecting rod 21 isadjustably connected and adequately sealed to this end of the bellows 22 and, as seen in Figures 3 and 15, its opposite end is connected by a crank pin 28 to a gear sector 29. The gear sector 29 is pivotally mounted on and held. in position by shouldered, split bushing 30, extending between and supported by two horizontal ribs extending across the instrument frame :6 in a manner which will be apparent from Figure 5. The gear sector 29 has a toothed portion 3| which is adapted to mesh with teeth 32 formed on'the upper end of a gear shaft 33. Referring back to Figure 2 it will be seen that the gear'shaft 33 extends to the lower portion of the instrument frame I6 being journalled in ball bearings 34 mounted in a central tubular portion of the frame l6 to the end that the shaft 33 will be held rigidly against forces tending to move it in a longitudinal direction while free rotation thereof will be permitted. The shaft 33 is provided with flattened surfaces 35 intermediate the ends thereof and the lower end has a threaded portion 36 adapted to mate with in- -ternal threads of a thimble 31 which projects into and forms a reinforcing portion for the upper head of a density bellows 38. The lower head 39 of the bellows 38 is adjustably attached by a This frame threaded stud 48 and a nut 4| to a retainer frame 42 which surrounds bellows 38 in a manner to prevent lateral displacement thereof but to permit, and move with, longitudinal displacements of the head 39. A cam 43 is fastened by a screw to the upper surface of the retainer frame 42 and an annular extension 45 of the frame 42 projects upwardly through a central opening in the cam 43. A bushing 46 within the extension 45 is provided with internally flattened surfaces to mate with the flattened surface 35 of the shaft 33.

,It will be noted that the cam 43 is of considerable thickness and in its contour differs between difierent horizontal sections thereof ina manner hereinafter more fully described. ever be seen from the structure of the parts so far described that the bellows 38 together with its retaining frame 42 and the cam 43 which is mounted thereon will rotate with the shaft 33 and itwill further be seen that whilethe shaft 33 is held against longitudinal movements nevertheless the head 39 of the bellows 38 will move upwardly or downwardly as the pressure upon the exterior of the bellows 38 varies relative to the pressure upon the interior of this bellows. The frame 42 will also move up and down with the head 39 and accordingly the cam 43 will likewise move with the frame.

Referring back to Figure 1, it will be seen that the means for varying the pressure upon the exterior of the bellows 38 comprises a conduit 41 which is communicatively connected with an impact tube 48 opening against the direction of flow of the air flowing through the air intake duct 7. The conduit 4! leads to a threaded opening 49 extending through the wall of the casing l5 and a return conduit 58 leads from a second threaded opening 5| to a tube 5| which opens in the direction of the flow of air through the air intake 1 at a point adjacent the discharge end of the venturi H.

It will be seen that the pressure conditions within the control regulator I3 and upon the exterior of the density bellows 38 as well as upon the exterior of the bellows 22 will simulate the density conditions around the venturi ll allowing fora certain mass flow of air in the conduits 41 and '56. The differential pressure created by the mass flow of air through the venturi ll being transmitted to the interior of the bellows 22 g by a conduit I2 and the exterior thereof by the conduits 41 and 58 is translated by the mechanism comprising the gear segment 29 and a gear shaft 33 into angular movements of the cam 43 while the differences between the fixed density within the bellows 38 and the variable. density upon the exterior thereof results in a vertical adjustment of the cam 43 along the gear shaft 33. The contour of the cam 43 will be more particularly described in connection with figures I I et seq. For the moment it will sufiice to say that the variations in the contour both angularly and longitudinally of the cam are effective to actuate a bell crank 52 one end of which is-in contact with the cam through a contact screw 53 which is adjustable in a lower horizontal portion 54 of the crank. The bell crank 52 is formed with an upwardly extending portion 55 and a second horizontally extending portion or arm 56. A pivot bearing 51 is provided in the arm 56 adjacent the vertical portion 55 and the opposite end terminates in a The contacts upon this yoke It will howserve tanks 59, 69, and GI (see Fig. 1) which are selectively connected, by a three way valve 62 to a filter 53, and thence by way of a conduit 66 to an engine driven pump 65. In starting a manual pump 66 provided in a by-pass conduit 61 is utilever I 89 is so positioned that a ball point screw I It at one end thereof is in contact with the cam I91. The lever Iflt comprises a horizontally exthe top of the vapor eliminator I6 are returned to the top of fuel tank 59by way of a return conduit 77 and the upper portion of the vapor eliminator II is connected to the return conduit IT by conduit I8. From the lower portion of the second vapor eliminator I5, supply conduit I9 leads to the V fuel injector III. This fuel injector Ii! may be either a fuel pump or a distributor suitable forms of either of which are well known in the art and commercially available. A return conduit 89 leads the excess fuel from the injector I0 back to the aspirator I5. I

Referring to Figure 4, it will be seen that the venturi 73 through which the fuel passes from the supply pump 65 to the injector I0 is formed integrally with the cover I4 of the ratio regulator.

A passage 8| leading from a portion of the venturi adjacent the discharge end thereof is connected by way of a passaged screw bolt 82, which extends through the cover It into an internally threaded bore of the instrument frame I6, and thence by way of passage 83 in said frame and passaged screw bolt 86 with the interior chamber 85 of a bellows 88. The screw'bolt 84 together with a fastening screw 87 act to rigidly secure the bellows B6 to the instrument frame and an adjustable screw 88 accessible from the interior of the instrument frame permits the adjustment of the bellows spring 89. The free end of the bellows 86 is operativ ely connected as shown in Fig. 3 by a connecting rod 9 3 with a crank pin ti on a gear segment 92 in a manner to oscillate the gear segment about its pivot 93. The opposite end of the connecting rod $9 is attached to the free end of a bellows M, the interior chamber 95 of which is connected by means of a passaged screw bolt 96 with a passage ii? in the instrument frame I6" and thence by way of a passaged screw bolt 98, which extendsthrough the cover It, with a passage 99 formed in the cover It which passage opens into the most restricted portion of the venturi I3. The connecting rod 99 is thus reciprocated as a result of the differential pressure created by the flow of fuel through the venturi I3 these movements being translated to angular movements of the gear segment 92 about its pivot 93. The teeth I 90 of the gear segment 92 (see Figu es 2 and 3) mesh with a toothed portion -I GI upon the lower end of a shaft IE2. This shaft is mounted in ball bearings to the cam plate I06 by a screw I08 and for this reason rotateswith the shaft I08. A contacttending portion III, a downwardly extending portion I I2 and a horizontally extending arm I I3. A bushing I It extends through a suitable opening in this portion of the lever to pivotally support the same. The lever terminates in a downwardly extending portion I I5 which carries two terminal clips H6 carrying contacts I" and H8. This downwardly extending portion N5 of the lever I09 extends as shown in Figure 7, between the'two forks of the'contact yoke 58 on the lever 52. This yoke carries contacts H9, I20, I2! and I22, arranged with two contacts in each of the forks of the yoke, these being aligned in pairs with the contacts II'I, II8 of lever I09.

Referring to Figure 9 which discloses the electrical circuit, the contacts H8 and II? of lever I09 are shown in a neutral position between the contacts H9, I29, I2! and I22 of the lever 52. The contacts H9 and I22 are electrically connected and have a common lead to a battery I23 the opposite pole of which is connected through a manual switch I25 to a lead A. A pilot light I25 is placed in a suitable shunt circuit to visually indicate to the'pilot that the battery circuit is closedand in operation. The lead A is connected directly to themotor panel and a'second lead B extends directly from these contacts to the motor panel. A lead C connects contact IIBdirectly with the motor panel and a, similar lead D conmotor panel. Contacts I2I and I20 are similarly and separately connected to the motor panel by leads E and F respectively. The lead A is connected in the motor housing to one of the. reversing switches designated Back on the drawings and thence by way of lead E to contact I2 I. A shunt from this lead A extends to the other of the reversing switches designated Forward on the drawings and thence back to the contact III by way of lead F and also by way of the field winding I27 to the lead B, and thereby directly with contacts I22 and H9.

The details of the motor control mechanism I25 will be seen in Figure 8 in which I28 indicates a housing having an end cap I29 which cap is provided with a projecting shank or ear I39 perforated for pivotal connection with a fuel control lever I3I of the fuel injector I0. An armature I32 is journalled within the housing I28 in suitable ball bearingsprovided in the motor housing and in the end cap I29. A shaft I33 of the armature extends through and is rigidly connected with a bushing IStwhich carries a driving gear I35. Ball bearing I36 positioned in a frame I31 and retained by a cover I38 provides a journal for the bushing I34 which rotates with the shaft I33.

-A gear and pinion I39 journalled in ball bearings gear I35 of the bushing I34 while the pinion meshes with gear MI formed at one end of a shaft I62. A countersunk portion M3 in the end of shaft I 32 retains a ball bearing I44 which provides a journal for a reduced end of the shaft I33. The shaft I412 is journalled in ball bearings I45, supported by the frame I31. The shaft I42 is provided at its oppos te end with a threaded portion I46 adapted to coact with internal threads in a hollow shaft It? which surrounds the shaft I42 for the major portion of its'length, and is flattened at its outer end to provide a perforated lower side of the shaft. A set screw I5I extends through the housing I29 and is provided with an end portion adapted to fit in the slot I49 in a manner to prevent angular movement of the shaft I41 but to permit longitudinal movements of the shaft for the length of the slot I49. A pair of contact pins I52 and I53 are adapted to project into the slot I50, in sucha manner that the contact pin I52 will be forced outwardly when the hollow shaft I 41 approaches its innermost position and .the contact pin I53 will be forced outwardly as shaft I41 approaches its outermost limit of travel. The contact pins I52 and I53 are positioned to actuate the reversing switches I54 which determine the direction of rotation of the rotor I32.

As shown in Figure 1, the entire motor control mechanism I25 is mounted for longitudinal displacement, one end being pivotally mounted to the fuel control lever I 3I and the other end being pivotally mounted by the ear I 48 to a crank I55 which crank is rigidly connected .to a shaft I55. A crank arm I 51 also mounted upon the shaft I55 is connected to a throttle rod I55 at a point intermediate the ends thereof. A throttle valve I59, positioned on the discharge side of the venturi II in the air intake passage 1, is operably connected to the rod I58 and may be adjusted, through throttle control lever I60, by the pilot to give any desired degree of throttle opening and corresponding setting of'fuel control lever I3I after which setting the desired fuel ratio is maintained regardless of changes in factors such as altitude "I is moved toward the left from the position shown in Figure 1 and the fuel supplied by the injector I0 is increased. The relative richness of the fuel air ratio of the mixture supplied to the engine ismaintained regardless of changes in elevation and this relative richness of the mixture may be altered by any new setting of the manual throttle I60 actuation of which will simultaneously incnase on decrease the quantity of fuel and alrsjnpplied to the engine.

Assuming that the contacts I" and II 0 are now separated from the contact H9 and I30 back by movement of the rod I30 into and out of the motor housing, under the influence of the integrator I3.

' The'operation of the electrical circuit in conjunction with the motor will now be described. Referring to Figure 9 it will be seen that when the switch I24 is closed, current is continuously supplied from the battery thromgh the lead A, the field coil I21 and back by way of lead B. The circuit through the armature of the motor comprises the leads C and D which terminate in the contacts I I1 and I I8, and this circuit is therefore normally open. If, however, the contacts II! and H8 are moved to the left of the position shown in Figure 9, a movement which is affected by relative motion of the levers 52 and I09, then the circuit will be closed between contacts I I1 and H9, and between H0 and I20 to the end that a closed circuit is provided between the lead D and opens the forward reversing switch so that current no longer flows through the armature of the motor. It will be seen that rotation of the motor in the forwarddirect on has the effect of increasing the overall length of the motor, that is, it will increase the distance'between the point at which the ear I49 is pivoted to the crank arm I 55 and the point at which the ear I30 is pivoted to the lever I 3 I. Accordingly the-upper end of lever coil I21,and lead B. As the contacts Ill and H8 move farther to the right relative to the other contacts, circuits will be closed through contacts I" and I2I and between H0 and I22. Accordingly the circuit through the armature I32 of the motor I26 will be closed through the leads C. and D but in this case the lead C will be connected by way of contact I22 with the negative pole of the battery I23, while the lead D will be connected to the battery by way of contacts II I and I2I, lead E and the back reversing switch and thence by way of lead A and switch I24 to the positive pole of the battery. The motor armature will now rotate in the opposite direction until the contact pin I52 is forced outwardly by the action of the end of the slot I50 as the shaft I41 moves longitudinally inward toward the motor, thus reversing the action previously described, the relative richness of the mixture now being decreased rather than increased.

The operation of the electrical circuit in connection with Figure 9 has been described with reference to movement of the contacts Ill and 0 to the right or to the left of the position shown in this figure. It will be understood this movement should be considered as being relative to the other contacts II9, I20, I2I and I 22, these contacts being mounted upon two forks of the yoke on the end of lever 52 are separately movable to the right or left'relative to the contact I" and H8 due to the action of the cam 43 acting through the contact screw 53 upon the bell crank 52. Thus it will be seen that movement of the four. outer contacts II9, I20, l2I and I22 is a Q function of the difference in density upon the exterior and interior of the density bellows 38 and of the mass flow of air through the venturi II which is made eifective upon the cam 43 through the action of the bellows 22. On the other hand the movement of the contacts II! and H8 between the yolk and of the lever 52 is a function of the differential pressure of the flow of fuel through the venturi I3 which pressure is made efiective through the bellows 86 and 94 acting through the intermediary of crank 90, crank pin 9|, gear segment 92, shaft I02 and cam I01 upon upper contact lever I09. to move the contacts I I1 and H8 within the confines of the yoke 50 regardless of the position of the latter. Thus it will be seen that the fuel air ratio is adjusted in accordance with an integration of several functicns including the mass flow of air through the air inlet of the engine, the air density condition within the air intake, and the flow of fuel to the supply means. This integration is effected by means of a mechanism embraced in a single housing all of the elements of which are mounted upon a single frame in such a manner that all station numbers.

parts thereof arereadily accessible for adjustment, repair or replacement.

-The layout of the fuel available cam I! is shown in Figure 10. The cam profile is marked Cam 1m Percent Perceint with station numbers the percentage of efiective 5 5mm Angle fronrcenter 3553 33%;; cam lift or percentage of capacity positionv of, which can be obtained from the following table. M468 1933 m .3568 21.35 21. as a Percent Cam 11ft .4 1 cit .339 29.8 30. statlon Hg 8 from center gg' g g Y I447 39142 541 530' 0.3392 17. 32 .400 420 58. 7 0' .3468 19. 35 .4732 45. 7 03. 0 7' .3550 21.2 .5001 50.1 09. 11-33' 3685 23. 72 .5101 53.25 72. 5' .3070 27.4 .542 53.4 711 .4130 32.0 .534 00.7 81. 28 0' .4270 35.4 6173 73.5 85. 32-12' .4370 37.4 .053 31.0 88. 36- 3' .4500 40.0 .712 92.4 04. 434s' .4698 43. 9s 791 10s. 2 105. 5027' .4370 47.45 .850 120.07 113. 57-27' .5020 50.4 .850 67-33 .5240 54.8 s930' .5055 03. 1 104 0; .5900 62 4-1 1 Along its long1tud1nal ax1s, the cam presents 39: 3 varying sections as may be seen in Figure 12, the 1-3 .3512 32- 3 profile at any given horizontal section corre- {9352 3 1232 8M2 g5 sponding to the fuel requirements for a definite 1 132 8% density condition. Sections corresponding to alti- 229 48I :75 100:1 tudes Of 5000 to +20,000 feet together With the gggZ-gj :83; sections corresponding to 5000 foot intervals bei l 7993 10919 tween these two positions have been marked on 3522-3 328 113-0 the drawings. The profile corresponding to an elevation of 5000 feet is shown in Figure 13.

The angular position of cam I01 can be accurately established; by means of the mechanism illustrated, having a definite relationship to the weight of the fuel passing through the Venturi constriction 13, this being eflicient over the flow and viscosity range encountered. The weight of fuel delivered by the injector It] varies directly with the rotative speed, position of capacity control lever l3l, and the specific gravity of the fuel. Sincethe specific gravity of the fuel now issued to service does not vary more than 1% and the performance of the injector is held within 1 it can be considered that the delivery of fuel by weight is affected only by the rotative speed and the setting of the capacity control lever 13!. In accordance with a generally accepted source of measurements as provided by the differential pressure across an orifice in the fuel line the weight of fuel delivered by the injector can be considered to vary as the square root of the differential pressure across the Venturi constriction 13 formed in the cover'member.

The differential pressure created by the flow of fuel through the Venturi constriction I3 having been transmitted by the communicating passages previously described to the interior of the 1 two bellows 86 and 94 is transmitted by the mechanism comprising the connecting rod 90 with the crank 9|, the gear segment 92, shaft I02, and con-- verted into angular movements of the cam I01. The layout of the cam may be made such that the following relationship exists:

Weight of fuel in lbs.

= /differential pressure across Venturi (13) /degrees cam rotation The layout of the fuel required cam 43 is shown in Figures 11 and 13. The cam is marked with The percentage of effective cam lift, also percentage of capacity position corrected for density changes of the air surrounding Venturi constriction II can be obtained for an altitude of 5 thousand feet from the follow- 1112' table:

In general a reference point on the curved outside contour of cam 43 may be determined as follows:

(a) The angularposition of this reference point in degrees of cam rotation varies with the weight'of the air being consumed by the airfuel-air ratio is determined by laboratory and flight tests of the engine and may vary for different types of engines.

It will be understood that in practice the con-. duits I2, 4'! and 50 between air intake 7 and the ratio integrator iii are preferably heat insulated so that the temperature condition present in the air intake I will prevail in the ratio integrator. This will insure that the density conditions within the regulator 13 will be the .same as within the intake 1 except for a certain mass flow of air through the conduits 41 and 50 correction for which can be made.

Having thus described the invention, what is claimed as new is: 1 i

1. A system for regulating the fuel-air ratio of an air-craft engine, a regulator including a housing, a removable frame within said housing, a plurality of pressure responsive devices mounted upon said frame, passaged. means providing. communication between one of said pressure responsive devices and a Venturi constriction in the air intake of the engine, passaged means providing communication between a Venturi constriction in a fuel supply conduit of theengine and another of said pressure responsive devices, said frame ed screw bolts extending through said cover into said frame for positioning said frame and providing communication between the passages in said cover and the passages in said frame,

intake of the engine, a gear shaft, means comprising a connecting rod and a gear segment for transmitting motion from said bellows to said shaft, a cam mounted upon said shaft for rotation therewith, a density bellows mounted upon said shaft for rotation therewith and having a free end wall movable in response to variations between the density of the air upon the interior and the exterior thereof, means for transmitting movements of said free end of said density bellows to move said cam longitudinally of said shaft, and means actuated by said cam for regulating the fuel supply of the engine, whereby the fuel-air ratio is maintained in accordance with a desired value for any given rate of flow of air to the engine at any given density thereof.

3. In a system for controlling the fuel-air ratio of an air craft engine, a regulator for controlling the operation of a fuel 'air ratio adjusting mechanism, said regulator including. a bellows, means providing communication between the interior of said bellows and a Venturi constriction in the air intake of the engine, a gear shaft, means comprising a connecting rod and a gear segment for transmitting motion from said bellows to said shaft, a cam mounted upon said shaft for rotation therewith, a second bellows, means for proasoaeae viding communication between the interior of said second bellows and a fuel supply line of said engine, a second shaft mounted coaxially with said first mentioned shaft, means comprising a connecting rod and gear segment for transmitting movements of said second bellows into angular movements of said shaft, a cam mounted upon said last mentioned shaft, and means independently responsive to the action of said cams and eifective to compare fuel andair flows to set the fuel control mechanism of the engine, whereby the quantity of fuel to the engine is adjusted to maintain a given ratio with the rate of flow of air to the engine.

4. In a system for controlling the fuel-air ratio of .an air-craft engine, a fuel-supply adlusting mechanism, a regulator for controlling the operation of said mechanism, said regulator including a bellows, means providing communication between the interior of said bellows and a Venturi constriction in the air intake of the engine, a gear shaft, means comprising a connecting rod and a gear segment for transmitting motion from said bellows to said shaft, a cam mounted upon said shaft for rotation therewith, a second bellows, means for providing communication between the interior of said bellows and a fuel supply line of said engine, a second shaft mounted coaxially with said first mentioned shaft and means comprising a connecting rod and gear sector for translating movements of said second bellows into angular movements of said second shaft, a cam mounted upon said second shaft, a pair of levers one of which is actuated by said first mentioned cam, and the other of which is actuated by said last mentioned cam, and electrical contacts mounted upon said levers operative to control the electrical circuit of a reversible motor for setting the fuel supply adjusting mechanism of the engine, whereby the fuel-air ratio is maintained at a desired value for any given rate of flow of air and fuel to the engine.

CONRAD A. TEICHERT, 

